Update nested field in BigQuery table

Question

I am trying to perform what, you would think, is a trivial operation in BigQuery; I am trying to update a nested field in a BigQuery table that is the result of a 360 export

Answer 1

If you need to modify a given custom dimension you can use this:

#standardSQL
UPDATE `tablename`
SET hits = 
  ARRAY(
    SELECT AS STRUCT * REPLACE(
      ARRAY(
        SELECT AS STRUCT cd.index,
          CASE WHEN cd.index = index_number THEN 'new value'
          ELSE cd.value
          END
        FROM UNNEST(customDimensions) AS cd
      ) AS customDimensions)
    FROM UNNEST(hits) hit
  )
WHERE TRUE

But it takes a while to run.